Aerospace Materials © 2011 Project Lead The Way, Inc. - PowerPoint Presentation

Slide1

Aerospace Materials

© 2011 Project Lead The Way, Inc.

Aerospace EngineeringSlide2

Commonly Used Aerospace MaterialsWoodSteelAluminum alloysTitanium alloysMagnesium alloysNickel alloysFiber-reinforced compositesSlide3

Factors for Selecting MaterialsFunction What is the component used for?Material Properties Strength to weight ratio Stiffness Toughness Resistance to corrosion Fatigue and effects of environmental heatingProduction Machinability Availability and consistency of materialSlide4

Cyclic StressesAverage commercial aircraft 30 year life cycle 60,000 Hours 2,500 Days – 357 weeks – 6.85 Years 20,000 Flights 667 flights per year 100,000 miles of taxiing 4 times around the Earth’s circumference

Total average maintenance and service cost are double the original purchase priceSlide5

Flight StressesPressure differential fuselage to outside 0 kPa to 60 kPa (8.6 psi)Temperature differential ground to cruise Ground temp to -56 oC (-69 oF)Impact load of landing Landing gear now supports aircraft Wings flex from upward lift force to downward force of their own

weight Tires accelerate from 0 kph to 400 kmph

(this creates a puff of smoke)Slide6

Keep in MindReducing material density reduces airframe weight and improves performance Fuel efficiency Climb rate G-force loadingMaterial density reductions are 3 to 5 times more effective than increasing tensile strength, modulus, or impact resistanceSlide7

Early Aircraft Built of WoodWright Brothers used SpruceWidely availableUniform piece to pieceGood strength to weight ratioDifferent properties in different directions Easy fabrication and repairSlide8

Aerospace Materials – WoodSensitivity to moistureRot and insect damageNatural product lower consistency than man-madeSlide9

Aerospace Materials – WoodRarely used today in production aircraftUsed today in homebuilt and specialty, low-volume productionChinese have selected oak for the heat shield of a reentry vehicleSlide10

Aerospace Materials – Metal AlloyMaterial FormsSheet ˂ 0.250in.Skin of fuselage, wings, control surfaces, etc.

Optional stamping dies videoSlide11

Aerospace Materials – Metal AlloyMaterial FormsPlate ˃ 0.250in.Machined into varying shapes and parts Forging – Material is plastically deformed by large compressive forces in closed dies Produces high strength non-uniform cross sectional partsSlide12

Aerospace Materials – Metal AlloyMaterial FormsExtrusion – Material is forced through dies to create a uniform cross sectionUses include stiffeners and ribs

Optional

metal extrusion videoSlide13

Aerospace Materials – Metal AlloyMaterial FormsCasting – Liquid material is solidified in a mold

Optional casting videoSlide14

Aerospace Materials – Aluminum AlloyCutting-edge (1920s-60s)Most abundant metal in the earth’s crustPure aluminum is relatively soft Slide15

Aerospace Materials – Aluminum AlloyCurrently most widely used materialReadily formedModerate costExcellent resistance to chemical corrosionExcellent strength to weight ratioSlide16

Aerospace Materials – Aluminum AlloyStrength and stiffness are affected by:Form Sheet Plate Bar Extrusion Forging Heat treating and tempering

Stronger

aluminum more brittleSlide17

Aerospace Materials – Aluminum AlloyMost common alloy is 2024 (24ST)93.5% aluminum, 4.4% copper, 1.5% manganese, and 0.6% magnesiumAlloy SeriesPrinciple Alloying Element1xxx99.000% minimum Aluminum2xxxCopper

3xxxSilicon Plus Copper and/or Magnesium4xxxSilicon

5xxxMagnesium6xxxUnused Series7xxxZinc8xxxTin9xxxOther ElementsSlide18

Aerospace Materials – Aluminum AlloyAluminum lithiumSame weight savings as composites but can be formed by standard techniquesHigh-strength applications – 7075 – 7050 – 7010Zinc, magnesium, and copperSheet aluminum is clad with a thin layer of pure aluminum for corrosion protectionSlide19

Aerospace Materials – Steel AlloySteel is very cheap and easy to fabricateFirst utilized in fuselage construction Steel tubing replaced wire-braced wood constructionToday’s applications: High strength and fatigue resistance Wing attachment fittingsHigh temperatures Firewalls and engine mounts Slide20

Aerospace Materials – Steel AlloyAlloy of iron and carbonCarbon adds strength to soft ironAs carbon content increases, strength and brittleness increaseTypical steel alloys are1% carbonOther common alloy materials – Chromium, molybdenum, nickel, and cobalt Slide21

Aerospace Materials – Steel AlloyProperties of steel are influenced by heat treating and tempering Same alloy can have moderate strength and good ductility or high strength and brittleness, depending

on heat treatmentMaterials temperature is raised to1400-1600 °F

- The point at which carbon goes into solid solution with the ironSlide22

Aerospace Materials – TitaniumGreater strength to weight ratio and stiffness than aluminum Capable of sustaining temperatures almost as high as steelCorrosion-resistantSlide23

Aerospace Materials – TitaniumDifficult to form High forming temperatures and stressesSeriously affected by any impuritiesMost impurity elements – Hydrogen, oxygen, and nitrogenHigher fabrication costExpensive – 5 to 10 times as much as aluminumSlide24

Aerospace Materials – TitaniumExtensively used in jet-engine componentsLower-speed aircraft, high-stress airframe componentsUses include landing gear beams and spindles for all moving tailsSlide25

Aerospace Materials – TitaniumSuper Plastic Forming/Diffusion Bonding (SPF/DB) Extreme temperature and pressure causes titanium to flow into the shape of the mold. Separate pieces of titanium are diffusion-bonded at the same time, forming a joint that is indistinguishable from the original metalSlide26

Aerospace Materials – Magnesium Good strength to weight ratioTolerates high temperaturesEasily formed – Casting, forging, and machiningUses include engine mounts, wheels, control hinges, brackets, stiffeners, fuel tanks, and wings Slide27

Aerospace Materials – Magnesium Prone to corrosion – must have a protective finishFlammableShould not be used in areas that are difficult to inspect or where the protective finish could erode awaySlide28

Aerospace Materials – High Temperature Nickel AlloysInconel, Rene 41, and Hastelloy Suitable for hypersonic aircraft and reentry vehicles

Hastelloy

is used primarily in engine partsSlide29

Heavier than aluminum and titaniumDifficult to formAerospace Materials – High Temperature Nickel AlloysSlide30

Aerospace Materials – CompositesMid 1960s and early 1970s Empennages of the F-14 and F-15Optional composites videoSlide31

Aerospace Materials – CompositesBoron/epoxy – horizontal stabilizers, rudders, and vertical finsMid-1970s carbon fibers Carbon/epoxy speed brake 1980s composite use expanded from 2% on the F15 to 27% on the AV-8B HarrierUses included wing

(skins and substructure), forward fuselage, and horizontal stabilizerSlide32

Aerospace Materials – Composites Modern fighters consist of 20% composite material 15-25% weight savings depending on structure Boeing 787 uses upward of 50% composites and includes composite wing and fuselageSlide33

High temperature resistanceUses include engine exhaust nozzlesSpace shuttle uses aluminum structure with heat-protective tilesAerospace Materials – CeramicSlide34

ResourcesBlack, T., & Kohser, R. (2008). Degarmo’s materials & processes in manufacturing. Danvers, MA: John Wiley & Sons, Inc.Hunt, E., Reid, D.,Space

, D., & Titlon, F. (2011).

Commercial airliner environmental control system. The Boeing Company. Retrieved from http://www.boeing.com/commercial/cabinair/ecs.pdf